Large power generation systems may provide megawatt class power generation capacity. Various large power generation system configurations may be used, including mirrors for focusing sunlight intensely on a small solar panel or collection of panels. In another large power generation system, there may be many thousands, even millions of photovoltaic panels employed. The panels may be electronically controlled to provide efficient power conversion and safe operation. A variety of apparatus and methods may be used to convert the DC power of a photovoltaic panel into AC power which may be provided to a load. Examples of conversion equipment include microinverters, inverters, and array converters.
As conversion efficiencies have improved, both for sunlight to DC electrical current and DC electrical current to AC power, capital costs have become increasingly important. The cost of installation and materials, for example the connectors and wiring between panels and between a string of panels and a consolidated distribution point, may be significantly increased by power generation systems employing a large number of panels. In some configurations the solar panels may be connected in a series-parallel arrangement, providing a powerful DC signal to a remotely located inverter system. Such a configuration may have several disadvantages. For example, extra wiring and connectors may be required between the solar panels and the inverter system, which may add both material and labor costs, as well as add transmission power losses. Also, an inverter controlling a string of solar panels may operate at a condition that maximizes the power provided by the entire string, which may result in sub-optimizing the power delivered by each individual panel, and therefore the power delivered by the entire string. Microinverters may be connected to each panel and may control a given panel to that panel's maximum power delivery condition, but the use of individual microinverters to provide a three phase electrical output may lead to increased cost and complexity of the microinverters and the power generation system. Single phase inverters may have an increased complexity due to their requirement to provide both positive and negative voltage signals, and may increase the number of switches and other components comprising a power generation system.